Hand pump



Patented Mar. 19, 1946 irs-D .STATES PATENT orties] .4 claims.

'This invention relates vto 'hand pumps fof the ytype used as emergency pumps for hydraulic -systems, especially in aircraft.

More particularly vthe presentinventionrelates to the construction of thefpistonof such pumps and has for its primary object 'the' provisionof Aa Apiston assembly which is Vconstructed and arranged to serve as a valve andmakes'it'unnecessary to employ the separate checkivalve assembly usually provided on or inthe pistonsofpumpsiof the character described, as well 'as reduces the number of parts, the manufacturing 'costs and the weight of the pump, compared to pumps as heretofore made.

Another object of my invention is'to provide a Vhand pump Vsuch as described .in Ywhich .the

piston is .slidable on the piston krod and the rod is provided with passages such that the piston will act as a most eflicient .pump valve controlling the flow through said passages, ,without the use of springs or parts other than the rod andpiston themselves, thus increasing the e'iciency of the pump compared to pumps requiring .separate check valve assemblies including valve members, valve seat members and valve seating springs.

With the foregoing objects .in view, vtogether with such other objects and advantages as may subsequently appear, theinvention residesnithe parts and in the combination, construction and arrangement of parts hereinafter described and claimed, and illustrated by wayvof examplelin the accompanying drawing, in which:

Fig. 1 isa fragmentary side elevation da hand pump in which the present invention .is emhodied;

Fig. 2 is an enlarged.fragmentary'longitudinal sectional view of the pump hereof -showing the position and valve actionof ,the .piston .during .the discharge stroke thereof;

Fig. 3 is a. sectional view corresponding .toFig '2" showing the position and valve action of .the

piston on the intake stroke thereof, there being shown a conventional form of intake check valve instead of the check valve shown in Fig. 2;

Fig. 4 is a cross sectional view taken on the line 4-4 of Fig. 3.

As shown in the accompanying drawing one embodiment of my improved pump includes a cylinder 5 having an intake port 6 at one end, a discharge port 'l at its other end and an intake check valve assembly `8 associated with said intake port.

Slidable through a stufling box 9 is a piston rod I0 carrying a piston head Il of special construction and arrangement. This rod is connected by means of a link I2 with a lever I3 fulcrumed as at Illyon a bracket I5 carried by the cylinder '5 so that upon manipulation of the lever the rod and piston-will reciprocate in the cylinder.

In accordance with my invention the piston assembly is constructed and arranged to serve as Aa check valve responsive to reciprocation of the piston assembly. As here shown this assembly is provided with a circular series of by-pass grooves or passages iii extending axially of and lin lonezend portion'of the rod, and the piston head is slidable relative to the rod so'as to control the flow of fluid through said passages or grooves. Thisgrooved end portion of the piston rod is re- 'duced vand provides a shoulder I'.' to limit the travel wof the piston head in one direction as shown in Fig. 2. When the piston head abutsfthe shoulder I'I as on the stroke of the piston in one direction (see arrows in Fig. 2), the intake ends I .S and the discharge ends I9 of the grooves or passages I6 remain open for the free flow of iiuid through the passages, between the piston head andpiston rod as shown in Fig. 2. In this connection it is seen that the passages I@ are of greater length than the piston and that the discharge ends .I9 extend through the shoulder II so as to remain open when the piston head abuts said shoulder.

On the stroke of the piston head in the other direction (toward the discharge port as per the arrow in Fig. 3), said head slides into abutting relation to a Washer-like stop ring 20 held on the reduced extremity ZI of said rod by a snap ring 22, as shown inFig. 3. In this position the piston head closes the intake ends IB of the grooves vor passages I 6 thus preventing flow of fluid past the piston head, whereupon the check assembly opens for intakingof fluid.

LAshere shown the piston II is in the form of ,a onefpiece annulus having its axial diameter less than its diameter and has a sliding *t on therod `li'land against the wall of the cylinder 5, .there beinga ring groove 23 in the piston containing an elastic sealing ring 2li which prevents leakage between the cylinder wall and the piston. A similar sealing ring 25 is carried on the rod I@ between the intake ends I 8 of the passages I6 and the stop ring 20, so as to form a seal between the piston and rod when the piston is in position to close the intake ends I8 of the grooves I6 thus preventing leakage between the piston and rod when the latter are moved in the direction of the arrow shown in Fig. 3.

It is now apparent that by the simple expedient of slidably mounting the piston l I on the rod I0 and forming the simple grooves I6 in the rod, a

most eicient pump valve is provided to control the pump action without necessitating the use of parts separate from the rod and piston, thereby greatly simplifying the construction of the pump and materially reducing its weight as well as its production cost.

As shown in Fig. 2 the checkpvalve assembly 8 includes a sleeve 21 socketed in Aone end of the cylinder 5 with its upper end registering with the intake port 6 and supportingva valve l seat member 28 for an inwardly opening ball valve 2S urged outwardly against its seat by'a spring 30 mounted in said sleeve. This assembly is held in place by a snap rings l The sleeve has a port 32 opening into the bore of cylinder 5, This check valve assembly requires but little Vrod to form a duid-tight seal between said rod and the surface of the inner periphery of the machining for its adaptation to the pump and as shown in Fig. 2

vand the wall structure ofthe intake end of the cylinder as shown in Fig. 3 actas stop to limit the stroke of the piston assembly in one direction whereas a stop ring 3S on the piston rod strikes the stuing box 9 to limit the stroke in the other direction. Y 1

While the piston-valve unit hereof is here shown as embodied in a pump it is to be understood that such a unit may be used in any other mechanism or device where` the valve action as herein provided is desired in connection with a piston-likemember and a piston rod member.

While AI have'shown and described specific embodiments of my invention, I do not limit myself Vto the exact details of construction set forth, and the invention embraces such changes, modifications and equivalents of the parts and their formation and arrangement as come within th purview 0f the appended claims. I claim:

l. In a hand pump, a cylinder having an intake port and a discharge port, an inwardly opening check valve controlling said intake port, a piston assembly in said cylinder having a passage for establishing communication between 'said ports and including` a piston rod and an head when the latter is in position for closingk saidpassa'ges.

3. In' a piston-valve unit, a piston rod having a uidgby-pass'passage extending axially thereof andgopening at its ends on the periphery of said rod, an annular piston head mounted on said rod for sliding movement relative thereto intoA vand out of positions in which the piston head opens and closes said passage to ow of iluid therethrough, a stop means for limiting the relative movement of the piston head in one direction to a position in which the passage is closed at one end by the piston head to prevent flow of fluid therethrough', and other stop means for limiting the relative movement of the piston in the opposite direction to a position in which the piston head uncovers the other ends of said passage whereby uid may now therethrough, and a sealing ring surrounding said piston and positioned to be engaged'by the inner periphery of said annular piston head when the latter is in engagement with the first recited stop means.

4. In a piston valve unit, a piston rod having a grooved portion which provides a plurality of axially extending groove passages in its periphery, said grooved portion throughout the greater part of its axial extent occupying a diametrically reduced end portion of the piston, the piston having a smooth or un-grooved periphery adjacent the .extremity of said end portion, a stop ring surrounding said smooth piston portion, a small part of the extremity of the piston having a further diametrical reduction, said stop ring fitting around the latter piston part and abutting against the annular shoulder resulting therefrom, a snap ring occupying a groove in said piston rod and positioned to prevent said stop ring from moving away from said shoulder, and an annular piston head of less axial extent than said grooved piston rod portion tted slidably therearound and slidable against and away from said stop ring to open and close iluid flow through said passages, there being in the inner part of the grooved portion of the piston rod stop shoulders produced by its diametrical reduced portion Vto limit the inward movement of said piston head.

GEORGE W. PLUMB. 

